DISH is a culture-driven organization. If you like the culture and are focused on results you'll likely thrive. If you don't enjoy the culture, your time there will be death by a thousand cuts. You'll be surrounded by equally focused people, and in almost every case the management team is doing everything they can to help you succeed.
I have worked at Dish Technologies for over a year now, and while I have enjoyed the project I work on daily, I don't feel I fit in well with the corporate culture. I gained valuable experience working for such a large company, and I recommend working there if that appeals to you.
I worked at SlingMedia/Dish for four years on various technology initiatives. It is trying to build a culture of Creativity, Pride, Adventure and Winning with nearly 16K employees that span satellite, internet and wireless services, it is a major challenge. It will be a great place to work once wireless deal is completed.